Feedback pneumatic amplifier

ABSTRACT

A fluid amplifier having mechanism for providing increased gain in amplification. The mechanism includes feedback means interposed between the output and control ports of the amplifier. The feedback means is provided with adjustable gates and to obtain maximum gain, the feedback is adjusted to a point slightly below that required for oscillation, for any selected main supply flow. At this point the mass flow of gas, through the control ports, which is necessary to cause the amplifier to switch is very small.

United States Patent [111 3,6 13,70

[72] lnventor William H. Hodges 3,261,372 7/1966 Burton 137/815 1038 Toney Drive, S.E., Huntsville, Ala. 3,456,665 7/1969 Pavlin............ 137/815 35802 3,465,772 9/1969 Monge et al. 137/815 [21] Appl. No. 748 [22] Filed Jan. 5,1970 [45] Patented Oct. 19, 1971 Primary Examiner-William R. Cline Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Harold W. Hilton [54] FEEDBACK PNEUMATIC AMPLIFIER 3 Claims 4 Drawing Figs ABSTRACT: A fluid amplifier having mechanism for provid- [52] U.S.Cl l37/81.5 ing increased gain in amplification. The mechanism includes [51] 1nt.Cl Fl5c 1/16 feedback means interposed between the output and control [50] Field of Search 137/815; ports of the amplifier. The feedback means is provided with 251/118, 121, 326 adjustable gates and to obtain maximum gain, the feedback is adjusted to a point slightly below that required for oscillation,

[ 1 References Cited for any selected main supply flow. At this point the mass flow UNITED STATES PATENTS of gas, through the control ports, which is necessary to cause 3,024,805 3/1962 Horton 137/815 e amp ifier to switch is very small.

FEEDBACK PNEUMATIC AMPLIFIER BACKGROUND OF THE INVENTION As oscillating fluidic element can be designed from the basic digital device in a number of ways. However, all of these designs utilize some means of providing feedback to cause switching.

A first type of oscillator, for example, utilizes a single' feedback loop connecting the control ports. Thus, when the power stream switches to one wall, a rarefaction wave is propagated in the control port at this side and a pressure wave develops in the control port on the other side. These waves cross each other and when they arrive at the opposite control ports, the power jet is switched.

Another type of oscillator utilizes a pair of feedback loops, with each loop communicating with a control port and an exit port. In this type of oscillator a small portion of the flow is captured in the feedback loop as the stream passes down one of the exit channels. This flow is directed to the interaction region as a control stream which causes the power stream to switch to the opposite side where the sequence is repeated. However, in any of the above-described oscillators, the mass flow rate of the gas is a factor which determines the switching response of the amplifier. Typically, each valve body is provided with feedback channels of fixed dimensions to provide a desired mass flow rate. Each valve body, therefore, must be designed for a desired application. Applicants device, on the other hand, is provided with adjustable gates whereby the gain may be tuned to a desired level for a given flow rate.

It is, therefore, an object of the present invention to provide a fluid amplifier with tunable feedback means.

Other objects and advantages of the present invention will be more readily apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view partially in section of the device of the present invention.

FIG. 2 is an elevational side view of the device of FIG. 1.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2 illustrating the intermediate plate used in fabricating the device.

FIG. 4 is a sectional view taken along line 44 of FIG. 2 illustrating the upper plate used in fabricating the device.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, a fluid amplifier is shown to include a main valve body 12 having an inlet 14 and a pair of exit ports 16 and 18 which communicates through a receiving chamber 20 with the inlet 14. A pair of control ports 22 and 24 is provided on opposite sides of main valve body 12 in communication with receiving chamber 20 and with a source of fluidic pressure (not shown).

The valve body assembly includes an upper plate 19, (FIGS. 2 and 4) and an intennediate plate 21 (FIGS. 2 and 3) secured in parallel, stacked relation on main body 12, as shown in FIG. 2. Intermediate plate 21 (FIGS. 2 and 3) is provided with a pair of openings 23 and 25 which communicate with a pair of feedback chambers 27 and 29 provided in main body 12.

A pair of feedback loops generally designated by the numerals 26 and 28 are provided and include a pair of feedback passages 30 and 31 communicating between the feedback chambers 27 and 29 respectively, and the opposite sides of the receiving chamber. Feedback chamber 27 communicates with exit port 16 through a passage 32 (FIG. 4) provided on the underside of upperplate l9 and a groove 33 provided on an end plate 35 of the valve assembly.

In like manner, feedback chamber 29 communicates with exit port 18 through asecond passage 37 provided on the underside of plate 19 and a second groove 39 in end plate 35.

A splitter 41 separates the exit ports 16 and 18 and includes a pair of cutaway surfaces 43 and 45 which extend on opposite sides of the splitter in communication with grooves 33 and 39,

reslpectively, of end plate 35.

pair of ad usta le gates are provided for restricting the passages-30 and 31 of feedback loops 26 and 28. The gates include a pair of screws 34 and 36 having a pair of closure members 38 and 40 respectively attached thereto. The screws are for insertion into a pair of tapped holes 42 and 44, respectively. The gates 38 and 40 are disposed for displacement in a pair of passages 41 and 43 respectively which communicate with passages 30 and 31 and the exterior of the body on opposite sides thereof. Thus, as the screws 34 and 36 are inserted into the body, gates 41 and 43 restrict the opening of passages 30 and 31, respectively, a desired amount. The amount of restriction is dependent upon the depth of insertion of screws 34 and 36 into the body.

A description of operation of this particular unit will aid understanding of constructional details. If fluid is injected in the main inlet 14 and passes into chamber 20, it would divide equally between the outlets 16 and 18. By supplying a control pulse of fluid into control inlet 22, fluid will flow along wall 50 and out of outlet 18. A portion of the fluid is directed along surface 45 of splitter 41 and upwards in opening 39 of end plate 35 and down groove 37 on the underside of upper plate 19, to be directed through opening 23 in intermediate plate 21 and into feedback chamber 29. The gas then flows down feedback passage 31 to enter the receiving chamber 20 and impinge on the gas on the side opposite the side being initially impinged. This action diverts the flow through outlet 16 where the action is then repeated to provide an oscillatory function. Thus, it can be seen that an oscillatory function occurs once the valve has been started.

The gates are inserted for adjustment to restrict feedback passages 26 and 28 as desired, depending on the mass flow rate of the fluid. Maximum gain is achieved by adjusting the gates to a point just below that required for oscillation. At this point the mass flow of gas, through the control ports is very small, in comparison with that which would be required without feedback.

lclaim:

1. A feedback fluid amplifier having means for varying the amount of feedback therein comprising: a body having a pair of outlets, a receiving chamber disposed in communication with a source of power fluid and said outlets; control means disposed for selectively directing said power fluid through said outlets, said control means including a pair of control ports one of each said pair of control ports being disposed on opposite sides of said body in communication with said receiving chamber; feedback means including a pair of feedback passages, each of said passages disposed in communication with one of said outlets and one of said control ports for feeding back a portion of said power fluid into one of said pair of control ports for deflecting the power fluid; and tuning means for adjustably tuning said feedback means for varying the amount of feedback to said control ports, said tuning means including a pair of closure members each of said closure members being slidably carried in said body on opposite sides thereof intermediate said control ports and said outlets, said closure members disposed for displacement to vary the opening of said feedback passages to vary the amount of said power fluid being fed back to each of said control ports.

2. Apparatus as set forth in claim I wherein said body is provided with a pair of apertures each respectively located in communication with a corresponding feedback passage, said closure members being mounted for slidable movement in said apertures to restrict the opening of said feedback passages, and support means secured to the outside of said body for slidably supporting said closure members in said apertures.

3. Apparatus as set forth in claim 2 wherein said support means includes a screw supporting said closure member thereon, said body being provided with a threaded opening to receive said screw therein, whereby said closure member is displaced in said aperture in proportion to the extent of insertion of said screw in said threaded opening. 

1. A feedback fluid amplifier having means for varying the amount of feedback therein comprising: a body having a pair of outlets, a receiving chamber disposed in communication with a source of power fluid and said outlets; control means disposed for selectively directing said power fluid through said outlets, said control means including a pair of control ports one of each said pair of control ports being disposed on opposite sides of said body in communication with said receiving chamber; feedback means including a pair of feedback passages, each of said passages disposed in communication with one of said outlets and one of said control ports for feeding back a portion of said power fluid into one of said pair of control ports for deflecting the power fluid; and tuning means for adjustably tuning said feedback means for varying the amount of feedback to said control ports, said tuning means including a pair of closure members each of said closure members being slidably carried in said body on opposite sides thereof intermediate said control ports and said outlets, said closure members disposed for displacement to vary the opening of said feedback passages to vary the amount of said power fluid being fed back to each of said control ports.
 2. Apparatus as set forth in claim 1 wherein said body is provided with a pair of apertures each respectively located in communication with a corresponding feedback passage, said closure members being mounted for slidable movement in said apertures to restrict the opening of said feedback passages, and support means secured to the outside of said body for slidably supporting said closure members in said apertures.
 3. Apparatus as set forth in claim 2 wherein said support means includes a screw supporting said closure member thereon, said body being provided with a threaded opening to receive said screw therein, whereby said closure member is displaced in said aperture in proportion to the extent of insertion of said screw in said threaded opening. 